1. Field of the Invention
The present invention is directed generally to truck bodies designed specifically for refuse hauling and, more particularly, to an improved rear transfer bracing system for a rear loading compactor refuse hauling truck body which enables the tailgate assembly and thus the center of gravity of the payload to be moved forward toward the front axle to improve load balance.
2. Related Art
Refuse pick-up trucks and other specialty vehicles commonly include a standard truck chassis fitted with a distinctly configured separate body that is designed and built to be installed on and to coordinate with the particular chassis. Normally, the truck chassis is obtained from a different manufacturer by the manufacturer of the truck body, the truck body installed on the chassis and the entire unit thereafter sold by the manufacturer of the truck body. The refuse truck body itself is, then, specifically designed for receiving, compacting, hauling and discharging refuse materials and includes all the associated operating mechanisms. One successful design for refuse hauling truck bodies, commonly known as a "rear loader", includes a main refuse hauling reservoir accessible for loading and discharge from the rear of the vehicle. An hydraulic compacting mechanism repeatedly compacts the refuse after each loading. In this manner, refuse eventually fills the available or usable reservoir volume extending from the front end back toward the rear of the body until no more material can be compacted.
Refuse is loaded through a rather large, heavy tailgate section which includes a receiving hopper into which general refuse, cans or the like, can readily be dumped and from which the large container or holding reservoir is loaded or packed. A packer blade mechanism operated by hydraulic cylinders moves the refuse from the hopper sweeping it into the body of the vehicle and compacting it therein. Both the hopper and the packer blade mechanism are contained in and supported by the tailgate section which extends in cantilever fashion for quite a distance, behind the rear wheels. The tailgate section is connected to the truck body by hinges at the top rear; the bottom of the tailgate section is normally latched to the rear structural supports on either side of the refuse truck body. During ejection of the accumulated contents at a landfill, or the like, the tailgate is unlatched and swung upward up out of the way while the contents of the reservoir are ejected utilizing a cylinder-operated ejection mechanism in a well-known manner.
The ejection mechanism, itself, includes a rather large sweeping wall or blade structure which forms the forward wall of the truck body against which the refuse is compacted during loading and moves aft in the manner of a plow to expel the entire contents of the refuse volume during ejection. Typically, the ejection mechanism is supported from a plurality of load bearing sliders which ride in a trough recess in the truck body floor. A telescoping ejection cylinder in the trough is connected to and operates the ejection mechanism back and forth. When the cylinder is fully retracted or collapsed, the ejector is in the fully forward position; and when the cylinder is fully extended, the ejector mechanism is fully aft in the truck body.
More importantly, however, with regard to load distribution, the ejection cylinder, even though it be a telescoping cylinder, in its fully retracted position still requires a considerable amount of space behind the cab. To accommodate the cylinder, the lower part of the ejector mechanism is angled sharply toward the rear of the truck body. This creates a wedge-shaped void space behind the cab that produces a rearward shift in the center of gravity of the payload.
The rather large, heavy tailgate section, which includes the lift and compacting mechanisms, extends beyond the end of the truck chassis a considerable distance creating a rather lengthy overhang with respect to the rear wheels of the truck. This puts additional loading on the rear wheels which, when combined with the effect of the wedge-shaped void of the lower portion of the front of the reservoir, results in an overall load distribution which is centered too far rearward with respect to the truck chassis. Too great a share of the load is carried by the rear wheels. Payloads, in fact, may be reduced simply because the resulting load distribution places so much of the load over the rear wheel assembly that is exceeds the legal axle load limit before the truck is fully loaded.
Redistribution is difficult for several reasons. The distance between the tailgate and the rear axle cannot readily be shortened because the truck chassis must extend rearward beyond the rear wheel carriage to accommodate large leaf springs which support the weight carried by the rear wheels. Because the chassis cannot be shortened beyond the end of the rear springs and spring supports, the shortest distance that can separate the rear wheels from the end of the truck body and, thus, the forward edge of the tailgate, is fixed. The loading trough of the tailgate, of course, must extend downward behind the end of the truck chassis.
Further, because of the very large weights and stresses involved with the load, tailgate and associated mechanisms, a heavy continuous lower rear transfer brace is required to be placed across the width of the truck body. This brace is at the same level as the main longitudinal truck chassis members and extends across the ends thereof usually abutting them.
Given the weight and design limitations that exist, it is apparent that any modification of the truck body or body/chassis interface which results in shifting the center of gravity of the load, tailgate and body forward even a small distance so that more weight is carried by the front axle would be difficult but extremely desirable. It would possibly increase the total legal payload for the refuse hauling vehicle, and also provide a safer load in terms of balance improving steerability and the general control which the driver has over the vehicle.